U.S. Pat. No. 4,531,761 (corresponding to DE 32 17 959) discloses a subframe bearing with a bushing subassembly that is held to a subframe (support member) at one end by a flange in the outer metal tube. The outer tube is vulcanized in the elastomer. At the other end the subassembly is held to the subframe only by the elastomer itself in the form of a tension pad or bumper-resilient limit flange. The bearing is mounted in a vehicle part by pressing the rubber bush with a tight fit into the subframe. The rubber tension pad or bumper lower resilient limit flange, facing away from the flange of the outer tube, is correspondingly compressed in a radial direction. When the rubber bush reaches its final installation position, the rubber tension pad comes out of the subframe, expands in a radial direction, engages over the edge of the subframe and forms an axial stop and a buffer for a stop plate. The stop plate is arranged on the clamping screw passing through the bushing subassembly and screwed to the other vehicle part to limit the axial travel of the support bearing in one direction.
The rubber bush is exposed to especially high stresses in the axial direction. Although mounted in the subframe with a high radial prestress, the bush subassembly may shift axially. The stop formed by the rubber tension pad engaging behind the edge of the subframe may be overcome, and the bush subassembly may be drawn into the subframe.
U.S. Pat. No. 5,127,698 (corresponding to DE 40 11 827) discloses a support bearing that prevents shifting of the rubber bush subassembly in the subframe even under the influence of relatively high vibrations. A bush endpiece, facing away from the end flange of the outer tube, is provided with supporting elements which, after radial expansion, engage snap-like behind the edge of the subframe or receiving lug. This presents a metal backed radially extending flange. At an axial distance from the edge of the subframe the supporting elements are adjacent to an abutment provided in the bush endpiece. The structure requires vulcanizing in both the outer tube with end flange as well as a plurality of supporting elements. This presents complications and adds cost to the manufacturing of such a support bearing.
U.S. Pat. No. 5,103,529 (corresponding to DE 40 11 854) discloses a support bearing with a bushing subassembly that is held to a subframe (support member) at one end by a flange in the outer metal tube which is vulcanized in the elastomer. At the other end the subassembly is held to the subframe by an elastomer tension pad (bulge or bead). After the bushing subassembly has been introduced into the subframe, a spring ring is inserted such that the rubber bush can no longer shift in the subframe at that side. The spring ring, in an inwardly spread state, has a diameter larger than the inside diameter of the subframe. The structure requires additional actions during manufacturing and adds cost and complexity.
Support bearings have also been proposed in which the steel outer tube vulcanized in the elastomer bushing has flanges at both ends. This presents manufacturing costs and difficulties as the bushing subassembly is inserted into a subframe and subsequently a further step is required involving pressing the two flanges toward each other. This proves to be expensive. However, these flanges that form stops for maintaining the position of the bushing subassembly guarantee the minimum pressing out force of 35 kN.
The previous solutions have also involved higher costs based on the provision of a two-component rubber bearing. The higher costs associated with a double vulcanization process is a drawback. Additionally, structures include a greater number of metal parts in the final rubber bearing than is desirable.